Capuchini Bone Chapel is a bit of an eye opener.
The Pantheon
We found an amazing bruschetta place here:
http://maps.google.com.au/maps/place?q=La+Bruschetteria+degli+Angeli&hl=en&cid=17237525976821756204
St Peter's Basilica is insane. The sheer scale of everything in there will knock you sideways.
Villa Borghese is a nice park, and there's a hill that overlooks the city.
The one thing I hated about Rome was getting about. The people walking along the streets tend to be very rude and will simply walk into you if you don't move. Take extreme care crossing roads, it's insane. It seems as though traffic lights are simply ignored. Also, try to avoid the restaurants around the tourist areas, the prices are ludicrous.